Stabilized lubricating composition



United States Paten a STABILIZED LUunrcAriNo COMPOSITION Edwin 0. Hook, New Canaan, and James B. Peeso, Stamford, Conn., assiguors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application June 27, 1952, derial No. 296,074

12 Claims. (Cl. 252-325) This invention relates to lubricating oil additives; to lubricating oil compositions containing the same; and particularly to those oils of the type known as crankcase oils. Although the improved lubricating oil compositions of the present invention are highly desirable for use in the crankcases of passenger automobiles, they are also especially valuable for heavy duty service in truck, bus, aeroplane, marine and diesel engines which operate for long periods of time at high temperatures.

The principal objects of the invention are to provide an improved lubricating oil of the heavy duty type which is heat stable, which is particularly resistant to sludge formation and oxidation, which is non-corrosive to alloy bearings and other metal parts under conditions of extreme service, and which is free from varnish formation and ring sticking tendencies.

When conventional lubricating oils are subjected to high operating temperatures for extended periods of time, such as are encountered in heavy duty service, they show a tendency to oxidize or decompose with the formation of complex and objectionable oxidation anddecomposition products. Under the high temperature conditions obtaining in theengine, these decomposition products polymerize to form lacquer-like deposits on or between the moving parts of the engine causing them to stick or to wear rapidly. Even larger quantities of polymerization products remain dispersed in the partly oxidized crankcase oil and are rapidly precipitated to form a sludge when the engine cools or when fresh oil is added to the engine. These precipitated sludges become caked on the heated metal surfaces and cut down the effective life of the engine.

in United States patent application Serial No. 132,995, now Patent No. 2,689,846, filed December 14, 1949, it is disclosed that hydrocarbon lubricating oil compositions having greatly improved detergent, anti-corrosive and anti-sludge forming properties may be prepared by the incorporation therein of minor amounts of various lubricating oil additives comprising terpene-phosphorus pentasulfide-sulfur reaction products. While the lubricating oil compositions containing these organic lubricating oil additives are extremely resistant to sludge formation under conditions of heavy duty service, We have found that, when preparing these improved lubricatingoil compositions from ordinary classes of lubricating oils which are not highly refined, a certain amount of sludge. will form when the oil is subjected to high temperatures in heavyduty service for long periods of time in the presence of air or oxygen. With the more highly refined oils, however, such as those treated by the solvent refining process, the amount of sludge formed under such conditions is small. Since it is desirable, however, to use a lower cost oil in trucks, buses, dieselengines, etc., which operate almost continuously at high temperatures, a further improvement in the heat stability of lubricating oils refined by conventional methods is desirable.

We have found that these organic terpene-PzSs-sulfur reaction products which are added tolubricating oils 2,734,866 Patented Feb. 14, 1956 refined by ordinary methods may be rendered more heat stable and more resistant to oxidation and decomposition and the lubricating oil compositions themselves may be made almost entirely resistant to sludge formation in heavy duty service for long periods of time at. elevated temperatures by the incorporation therein of minor amounts of oil soluble reaction products of phosphorus sulfides with either an ester of a tall oil fatty acid and an alcohol, or a mixture of a tall oil fatty acid and an alcohol, which reaction may be promoted by the presence of air or a free oxygen-containing gas.

The various terpene-PzSs-sulfur lubricating oil additives which possess-greatly improved anti-oxidantand anti-corrosion properties may be prepared by reacting phosphorous pentasulfide and various bicyclic terpenes with sulfur or a sulfurizing agent. The additional reacted sulfur in these additives greatly increases the desirability thereof over the prior art additives by virtue of their improved anti-oxidant and anti-corrosion properties. The pro-ducts, as will hereinafter be shown, provide a much greater degree of protection in the lubrication of internal combustion engines by preventing excessive cor-- rosion of the moving parts and by substantially eliminating oxidation of the lubricants employed therein.

it has been found that any of the bicyclic terpenes, namely those bicyclic hydrocarbons having the general formula CioHie, may be used in preparing the novel lubricating oil additives of the present invention. For example, satisfactory terpenes include alpha-pinene, betapinene, camphene, bornylene, nopinene (isomeric betapinene), fenchene, thujene, sabinene, carene, and the like bicyclic terpenes. The ordinary commercial grades of turpentine, most of which contain or more of alphapineue, are also included within the scope of the term bicyclic terpenes as employed in the present invention.

In preparing this class of lubricating oil additives, the selected terpene may be reacted with phosphorous pentasulfide and an additional sulfur-providing compound under relatively elevated temperatures and under atmospheric pressure. Ordinarily, the other components are added to the terpene constituent since the bicyclic terpenes are commonly liquids. While there is no upper limit as to the amount of terpene which may be employed, other than that of economic practicability, it is usually advantageous to employ only a small excess of terpene over the stoichiometric requirement to facilitate handling of the reaction product. For example, while only about 4 mols of terpene can be reacted with one mol ofphosphorous pentasulfide, it has been found that 6 mols of terpene will provide sufilcient liquid vehicle to permit easy handling of the reaction product.

While various sulfurizing agents may be employed in this reaction, elemental sulfur is the preferred material since its use eliminates the necessity of removing contaminating by-products or unreacted materials. it has been found that the amount of sulfur which may be reacted with the selected terpene and phosphorous pentasnlfide is within the range of from 0.5 mol to about 3 mols for each mol of P285 present. While amounts smaller than 0.5 mol per mol of P285 may be used, the increase in anti-oxidant properties of the reaction product is not sufficiently substantial to be of economic desirability. On the other hand, although the presence of relatively large amounts of sulfur in the lubricating oil additives is sometimes desirable, the presence of more than about 3 mols thereof for each mol of P285 causes crystalline material to settle out of the lubricating oil additive upon storage.

If desired, the sulfur, P285, and terpene may be reacted together. However, it has also been found that the terpene and P285 may be first reacted, and then the sulfur may be added and the mixture further reacted. Solvent extraction of the final reaction product has shown that the sulfur has reacted with the other components and is not merely in physical combination therewith.

The reaction between the terpene, PzS5,.and sulfur is mildly exothermic and may be easily carried out by heating the components to about 8090 C. and thereafter controlling the reaction temperature, as desired, according to the particular type of equipment employed. When an open reaction vessel is employed under atmospheric conditions, it is preferable that the reaction temperature be maintained below about 160 C. in order to prevent excessive evaporation of the terpene. On the other hand, where reflux equipment is used, superatmospheric pressures and more elevated temperatures may be resorted to if it is so desired. The reaction products in either instance are normally dark colored, relatively viscous liquids, which are readily soluble in hydrocarbon lubricating oils. Although numerous common organic solvents may be employed, as hereinbefore stated, it is preferable to use an excess of the particular terpene employed in order to facilitate handling of the components during and subsequent to the reaction.

The preparation of the terpene PzSs sulfur reaction products will be further illustrated by the following specific examples. It should be understood, however, that although these examples may describe certain specific features of the invention, they are given primarily for purposes of illustration and the invention, in its broadest aspects, is not limited thereto.

EXAMPLE 1 To 408 grams (3 mols) of alpha-pinene, with stirring, was added 111 grams (0.5 mol) of PzSs and 32 grams 1 mol) of sulfur. The mixture was heated for 2.5 hours at approximately 125 C. Thereafter, 300 grams of SAE grade hydrocarbon lubricating oil and 10 grams of a diatomaceous earth filter aid was added to the reacted material, after which the excess alpha-pinene was stripped off at a temperature of 125 C. and 12-15 mm. Hg. The oil concentrate was then filtered. To the product, which weighed 410 grams, was added 110 grams additional SAE 10 grade hydrocarbon lubricating oil to produce a 50% concentrate in oil of the product. The reaction product contained 3.6% of phosphorous and 14.0% of sulfur.

A sample of the product was tested as an anti-oxidant by the Underwood corrosion test using cadmium-silver alloy bearings as test material. A 1500 cc. sample of a Mid-Continent base lubricating oil of SAE 30 grade containing 0.4% by weight of the additive and 0.04% of iron naphthenate, based on the F6203 equivalent, as oxidation catalyst was heated for 10 hours at 325 F. while continuously spraying portions of the oil against two freshly sanded alloy bearings, the apparatus being so constructed as to permit free circulation of air. The total bearing loss was 4 milligrams, whereas the loss with a sample of the same oil containing the same quantity of iron naphthenate but no anti-oxidant was 1236 milligrams, while the oil viscosity increased over 300%. A sample containing a similar quantity of a PzSs-alphapinene reaction product prepared as described above but with no additional sulfur had a total bearing loss of 495 milligrams and a viscosity increase of 79%.

EXAMPLE 2 To 408 grams (3 mols) of alpha-pinene, with stirring, was added 111 grams (0.5 mol) of P2S5 and 8 grams (0.25 mol) of sulfur. The mixture was heated to 120-125 C. and maintained at a temperature below 143 C., the heating being continued for a period of 2.5 hours. Thereafter the reaction product was diluted with light grade, refined mineral lubricating oil, stripped, filtered, and prepared as a 50% concentrate in oil as described in Example 1. The product weighed 357 grams and contained 4.36% phosphorous and 12.46% of sulfur and was readily soluble in hydrocarbon lubricating oils.

4 EXAMPLE 3 To 408 grams (3 mols) of alpha-pinene, with stirring, was added 111 grams (0.5 mol) of P235 and 48 grams (1.5 mol) of sulfur. The mixture was heated for 2.5 hours at -125 C. Thereafter, the reaction product was diluted with mineral lubricating oil, stripped, filtered, and prepared as a 50% concentrate in oil according to the procedure described in Example 1. The product weighed 424 grams and contained 3.67% of phosphorus and 15.1% of sulfur.

A sample of the product was added to a Mid-Continent base SAE 30 grade lubricating oil to a 0.4% solution of the additive. The bearing corrosion loss was slightly greater than 1 milligram and the treated oil increased 19.5% in viscosity when the oil was tested as described in Example 1. A control sample of the product of reaction of PzSs and alpha-pinene had a bearing corrosion loss of 2844 milligrams when tested in a similar fashion, while the viscosity of the oil increased The various terpene-PzSs-sulfur reaction products described above are employed by us in our improved lubricating oil compositions, preferably in amounts ranging from 0.2 to 3% or more by weight and most commonly at a concentration of approximately 0.3% by weight.

Smaller amounts, 0.1 to 1.0% of the oil soluble reaction products of phosphorus sulfides and alcohol-acid esters or mixtures may be employed with the terpenic additives to enhance the heat stability thereof and such amounts will depend on the amount of terpene reaction product present. In a similar wa the greater the tendency of the terpenic additive to break down under high temperatures, the more heat stabilizer should be employed. The amount of both of these substituents in the oil will also depend to some extent upon the purpose for which the oil is intended. For example, an oil intended for extremely heavy duty service should contain more of both the terpenic additive and the heat stabilizer, as compared with the amounts required by an oil intended for ordinary usage.

The general chemical reactions and the preparation and nature of the oil soluble reaction products of the alcoholacid esters and the phosphorus sulfides such as phosphorus sesquisulfide, phosphorus pentasulfide, etc., involving the use of oxygen, are set forth in United States Patents 2,483,571, issued October 4, 1949, and 2,375,060, issued May 1, 1945, and reference thereto is incorporated herein.

The invention is particularly applicable to compositions comprising the terpene reaction products, previously described, and to those reaction products of phosphorus sequisulfide (P453) and the tall oil fatty acid-alcohol esters or mixtures.

As used herein, the term tall oil fatty acids is intended to refer to and include those fatty acids normally found in tall oil as well as those fatty acids having very similar properties as required for the specific purposes herein referred to. For the purposes of this invention, these acids contain 16 to 18 carbon atoms and may contain one, two or more unsaturated bonds. Representative acids of this group would include oleic acid, linoleic acid, linolenic acid, the corresponding C16 unsaturated acids, stearic acid, palmitic acid, or mixtures of the same. For example, a mixture of fatty acids derived from a tall oil distillation process normally comprises approximately 4060% linoleic acid with small quantities of other acids. Such a mixture has been found to be well suited for the application of the present inventive concept.

These tall oil fatty acids may be esterified with various alcohols prior to the reaction with phosphorus sulfide in the presence of an oxygen containing gas or they may merely form a mixture with these alcohols and then be reacted with the phosphorus sulfide in the presence of the oxygen-containing gas.

Among the alcohols suitable for use with the above mentioned acids, either for esterification purposes or merely to form mixtures therewith, are the aliphatic monohydroxy alcohols such as octadecanol, oleyl alcohol, butanol, lauryl alcohol, tridecyl alcohol, cetyl alcohol, octyl alcohol, isopropanol, etc.; the polyhydroxy alcohols such as ethylene glycol, propylene glycol; the alcohols containing aromatic or cycloaliphatic substituents such as octylphenoxyethanol, dihydroabietyl alcohol; the sterols such as B-sitosterol; etc.

The preparation of the oil soluble phosphorus sulfide reaction products of these esters or mixtures will be further described in greater detail by the following specific examples. It should be understood, however, that, although these examples may set forth in particular detail some of the more specific features of the invention, such is not to be construed as limitative thereof.

NoTE.The preparation of the octadecyl ester of Acintol FA #1 was as follows: (Acintol FA #1 is a mixture of tall oil fatty acids having from about 40 to about 60% oleic acid and from about 60 to about 40% linoleic acid and small percentages, approximately 35%, of other fatty acids.)

Materials used:

Octadecanol grams (1 mol) 268 Acintol FA #1 do 298 Toluene grams 500 Para toluene sulfuric acid do 4 The above materials were refluxed for three hours while removing the water which formed with a water trap. In this manner, 18 ml. or mol of water was removed. After washing with water, then with sodium carbonate, and again with water, the volatile materials were removed under vacuum at 100 C. to give 529 grams of the desired ester.

The ester, butanol, and sodium hydroxide solution were refluxed for 1V2-2 hours. The zinc chloride solution was then added to the mixture and refluxed for an additional 16 hour. After removing the water and butanol under vacuum at 100 C., the phosphorus sesquisulfide was added. After heating this reaction mixture to 130 C., a stream of air was blown into the reaction mixture. An exothermic reaction developed and white fumes were evolved. The reaction temperature was controlled by the rate of addition of air. After about one hour, the white fumes ceased, the exothermic reaction diminished, and air was passed through the mixture for an additional /2 hour, while holding the temperature at 130140 C. At this point, the zinc oxide and 10 ml. of water were added and the mixture heated for about /1 of an hour at 90100 C. The barium octahydrate was then added and the reaction gradually heated to 120 C., followed by blowing with air at this temperature to remove the water. After the removal of water was complete, 55 grams of Hy-Flo were added and the product filtered through a pre-coated, steam-jacketed vacuum filter. The resulting amber, oil-soluble liquid was the P4S3-oxygen-octadecyl ester of tall oil fatty acids reaction product and had the following analysis: Barium, 9.42%; zinc, 2.72%; phosphorus, 2.65%; sulfur, 1.63%. e

7 EXAMPLE Materials used: Grams Isopropyl ester of Acintol FA#1 (prepared in same manner as the ester used in Example 1 from isopropyl alcohol and Acintol FA 6 Butanol Sodium hydroxide (in 15 ml. of water) 13 Zinc chloride (in 25 ml. of water) 23 Phosphorus sesquisulfide 33 Zinc oxide 9 Barium hydroxide octahydrate 132 The above materials were reacted in the same general manner as set forth in Example 1.

The product which was obtained was the P4Ss-oxygenisopropyl ester of tall oil fatty acids reaction product and had the folowing analysis:

Ethylene glycol diester of Acintol FA #1 (prepared from ethylene glycol and Acintol FA #1 in the same general manner as the ester prepared for Example 1) 534 Butanol 135 Sodium hydroxide (in 25 ml. of water) 16 Zinc chloride (in 35 ml. of water) 28 Phosphorus sesquisulfide 40 Zinc oxide 11 Barium hydroxide octahydrate The above materials were reacted together in the same general manner as in Example 1. The clear amber oilsoluble liquid was the P-iss-oxygen-ethylene glycol ester of tall oil fatty acids reaction product and had the following analysis:

Percent Barium 6.2

Zinc 1.9

Phosphorus 1.8

Sulphur 1.6

EXAMPLE 1 Materials used: Grams Lauryl oleate (prepared from lauryl alcohol and oleic acid in the same general manner as the ester prepared for Example 1) 430 Butanol 100 Sodium hydroxide (in 20 ml. of water) 13 Zinc chloride (in 3.0 ml. of water) 23 Phosphorus sesquisulfide 33 Zinc oxide 9 Barium hydroxide octahydrate 132 The above materials were reacted in the same general manner as in Example 1. The resulting oil soluble amber liquid was the P4S3-oxygen-lauryl oleate reaction product and had the following analysis:

Oleyl stearate (prepared from oleyl alcohol and stcaric acid in the same general manner as the ester prepared for Example 1) 497 Butanol 75 Sodium hydroxide (in 15 ml. of water) 12 Zinc chloride in 25 ml. of water) 21 Phosphorus sesquisulfide 30 SAE #10 oil 497 Zinc oxide 8 Barium hydroxide octahydrate 124 The above materials were reacted together in the same general manner as in Example 1 with the exception that the oil was added at the same time as the zinc oxide. The resulting dark amber oil-soluble liquid was the P4Sa-oxygen-oleyl stearate reaction product and had the following analysis:

The octadecanol, oleic acid, butanol and sodium hydroxide solution were refluxed for about one hour. The zinc chloride solution was then added and the reaction mixture heated to reflux for an additional /2 hour. The water and butanol were removed by heating to l-l20 C. under vacuum. The phosphorus sesquisulfide was then added and after heating the reaction mixture to 125- 135 C., a stream of air was blown into the reaction. The exotherm which developed was maintained at 130- 140 C. by regulating the rate of addition of the air. At the conclusion of the exotherm, air blowing was continued for an additional /2 hour while maintaining the temperature at 130-140 C. The oil, zinc oxide, and 11 ml. of water were added to this mixture, which was then heated to 100 C. for about one hour. The barium hydroxide octahydrate was then added and the temperature slowly raised to 120 C. The reaction was maintained at 120 C. while air was blown through the reaction mixture to remove the water. After the removal of water was complete, 75 grams of Hy-Flo were added and the reaction mixture filtered through a steam-heated, pre-coated vacuum filter. The resulting dark amber oilsoluble liquid was the P4S3-oxygen reaction product of an octadecanol-oleic acid mixture and had the following analysis:

Percent Barium 4.97 Zinc 1.88 Phosphorus 1.5 Sulfur 0.9

EXAMPLE 10 Materials used: Grams Octadecanol 260 Acintol FA #1 286 Butanol 100 Sodium hydroxide (in 20 ml. of water) 17 Zinc chloride (in 35 ml. of water) 29 Phosphorus sesquisulfide 41 SAE #10 oil 546 Zinc oxide 11 Barium hydroxide octahydrate 164 Percent Barium 5.4 Zinc 1.7 Phosphorus 1.5 Sulfur 1.1

8 EXAMPLE 11 Materials used: Grams -Tridecyl alcohol 190 Oleic acid v282 Butanol Sodium hydroxide (in 20 ml. of water) 14 Zinc chloride (in 40 ml. of water) 25 Phosphorus sesquisulfide 35 Zinc oxide 9 Barium hydroxide octahydrate 142 The above materials were reacted together in the same general manner as in Example 6 with the exception that no oil was used. The resulting amber oil-soluble liquid was the P4S3-oxygen reaction product of tridecyl alcohol and oleic acid mixture and had the following analysis:

Percent Barium 9.6 Zinc 3.8 Phosphorus 2.9 Sulfur 1.0

The excellent compatibility and solubility of these oil soluble reaction products of phosphorus sulfides in hydrocarbon lubricating oil compositions leads to another important advantage, namely, the ease with which these compounds are blended with the oil compositions. This step is further simplified by our practice of very simply dissolving them in the lubricating oils up to the extent of 50% or higher concentration for storage and shipping purposes. In this way the blender of the ultimate composition need only pour the additive composition into the stock lubricating oil with suitable stirring in order to obtain the desired lubricant.

The invention will be further described in more specific detail by reference to and discussion of the following results obtained from heat stability tests which were run on various oil compositions selected to best illustrate the inventive concept.

These tests consisted of the following procedure: a 200 gram sample of the selected oil composition was placed in a 400 ml. short form, Pyrex beaker and set in a partially ventilated oven which was maintained at 250 F. The test sample was observed at regular intervals during a 125 hour period. After 125 hours, the sample was removed from the oven and allowed to stand and cool for 24 hours. The sample was then observed for hazing, precipitation and/or gelling. Precipitating and/or gelling were considered as failures; a small amount of precipitation or sedimentation, however, could be tolerated; hazing, although not a crucial factor, was an indication of heat instability.

The following results were noted on blends using a solvent refined Mid-Continent base oil, S. A. E. 10:

Table I Percent neu- Percent terpenegggggt g g g getadekcytli Hours Appearance of oil blend a y c Pentasnlflde Ester Heat Stabilizer (control) 125 Clear some darkening,

slight sediment. 48 Opaque, black. 24 Black, heavy precipitate. 24 Hazy, heavy precipitate. Clear, heavy precipitate.

96 Clear, some darkening,

very slight precipitate. 144 Clear, light precipitate. 120 Clear, light fuzzy precipitate. Clear, no precipitate.

From the foregoing tables, it will be realized that the addition of 0.3% terpenic additive alone rendered the oil blend unacceptable and a failure insofar as the heat stability thereof was concerned. The black, opaque appearance of the oil blend clearly indicated the lack of complete heat stability of the additive-containing oil. However, it is to be noted that the addition of as little as 0.3% of the heat stabilizer immediately improved the heat stability of the additive-containing oil so that the oil blend took on a clearer and lighter aspect. Improved results were similarly obtained when the concentration of the heat stabilizer was increased to 1.0 percent. It was found that, when lesser amounts of the terpenic additive were present, lesser amounts of the heat stabilizer were required, so that improvement was observed in some cases when as little as 0.1% heat stabilizer was added.

From the foregoing, it will be seen that we have provided a lubricating oil composition comprising a terpenic additive and a heat stabilizer, which composition is heat stable, is particularly resistant to sludge formation and oxidation, is non-corrosive to alloy bearings and other metal parts under conditions of extreme service, and is free of varnish formation and ring sticking tendencies.

Although We have described but a few specific preparations of the reaction products of phosphorus sulfides with esters and mixtures and have referred to the results of specific tests of such compounds in lubricating oil compositions containing terpenic additives, we consider the same not to be limited thereto. It is understood that suitable changes, variations and modifications may be made without departing from the spirit and scope of the invention.

We claim:

1. A hydrocarbon mineral lubricating oil composition comprising hydrocarbon mineral lubricating oil and, as an anti-oxidant and anti-corrosive agent having a tendency toward heat instability and the formation of sludge upon continued heating thereof at high temperatures, 0.23.0% by weight of a terpene-phosphorus sulfide-sulfur reaction product and, as a heat stabilizer, 03-10% by weight of a neutralized phosphorus sulfide-oxygen reaction product with a member of the group consisting of esters of alcohols and tall oil fatty acids and mixtures of alcohols and tall oil fatty acids.

2. The composition as defined in claim 1, wherein the alcohol is octadecanol.

3. The composition as defined in claim 1, wherein the alcohol is ethylene glycol.

4. The composition as defined in claim 1, wherein the alcohol is oleyl alcohol.

5. The composition as defined in claim 1, wherein the fatty acid comprises oleic acid.

6. The composition as defined in claim 1, wherein the fatty acid comprises linoleic acid.

7. The composition as defined in claim 1, wherein the fatty acid comprises from about 40-60% by weight of oleic acid and from about 60-40% by weight of linoleic acid.

8. The composition as defined in claim 1, wherein the fatty acid is stearic acid.

9. The composition as defined in claim 1 wherein the anti-oxidant and anti-corrosive agent is a terpenephosphorus pentasulfide reaction product and the heat stabilizer is a neutralized phosphorus sequisulfide-oxygen octadecyl-fatty acid ester.

10. The composition as defined in claim 1 wherein the anti-oxidant and anti-corrosive agent is a terpenephosphorus pentasulfide reaction product and the heat stabilizer is a neutralized phosphorus sequisulfide-oxygen octadecyl-fatty acid mixture.

11. The composition as defined in claim 1 wherein the anti-oxidant and anti-corrosive agent is an alpha pinenephosphorus pentasulfide reaction product and the heat stabilizer is a neutralized phosphorus sesquisulfide-oxygen octadecyl-18 carbon atom fatty acid ester.

12. The composition as defined in claim 1 wherein the anti-oxidant and anti-corrosive agent is an alpha pinenephosphorus pentasulfide reaction product and the heat stabilizer is a neutralized phosphorus sesquisulfide-oxygen octadecyl-IS carbon atom fatty acid mixture.

References Cited in the file of this patent UNITED STATES PATENTS 2,483,571 Brennan et a1 Oct. 4, 1949 2,515,222 Hoock et a1 July 18, 1950 2,654,712 Cyphers et a1. Oct. 6, 1953 

1. A HYDROCARBON MINERAL LUBRICATING OIL COMPOSITION COMPRISING HYDROCARBON MINERAL LUBRICATING OIL AND, AS AN ANTI-OXIDANT AND ANTI-CORROSIVE AGENT HAVING A TENDENCY TOWARD HEAT INSTABILITY AND THE FORMATION OF SLUDGE UPON CONTINUED HEATING THEREOF AT HIGH TEMPERATURES, 0.2-3.0% BY WEIGHT OF A TERPENE-PHOSPHORUS SULFIDE-SULFUR REACTION PRODUCT AND, AS A HEAT STABILIZER, 0.3-1.0% BY WEIGHT OF A NEUTRALIZED PHOSPHORUS SULFIDE-OXYGEN REACTION PRODUCT WITH A MEMBER OF THE GROUP CONSISTING OF ESTERS OF ALCOHOLS AND TALL OIL FATTY ACIDS AND MIXTURES OF ALCOHOLS AND TALL OIL FATTY ACIDS. 